Hi all, I'd like to discuss the API I'm proposing for the new url dispatcher I'm working on. I'll try to explain the API and some of the rationale behind it.
There is a working proof-of-concept at https://github.com/knbk/django/tree/url_dispatcher. Currently, all the names are chosen as not to conflict with the old implementation. A short description can be found at https://gist.github.com/knbk/96999abaab4ad4e5f8f9, which also contains a link to an example url configuration. My main goal was to create a simple, extensible API. In the old API, about 90% of the work was done in the `resolve()`, `_reverse_with_prefix()` and `populate()` of the RegexURLResolver. This made for a tightly coupled design that was almost impossible to extend. My starting point was the RegexURLResolver and RegexURLPattern. Both have a regex constraint that can match the current path and extract arguments. The former can then pass the remainder of the path to its list of resolvers and patterns; the latter can return a ResolverMatch containing the callback specified by that pattern. I've kept this distinction, with the `Resolver` and `View` classes. The change of name from `Pattern` to `View` is because the `View` object has a bit more logic that determines how the view is called. It is a thin, callable wrapper that can optionally decorate the actual view function with a set of decorators passed down from parent resolvers, and when overwritten, can do some more processing before or after the view function is called. The hard-coded dependence on a regex pattern has been abstracted to a Constraint object. Each Resolver and View has a (set of) Constraint object(s), that can match the current url and extract arguments. A RegexPattern that simply mimics the old behaviour will be available, but other implementations, such as a Constraint that matches the request's host or method, are easily provided. A Constraint can also reverse a set of arguments to a partial url. That means that the full set of constraints used to match an url to a view, together with a suitable set of arguments, can be reversed to the url itself. The main strength of a Constraint is that it can contain very specific logic about its arguments. For example, a Constraint may know that it resolves to a Model's primary key. If it then receives a Model instance of that particular type, it will know how to reverse that model instance to a valid string-based partial url, so that it can later be resolved to match the same object. It could also e.g. infer the regex pattern from the field's type. There's one final piece to the puzzle: the URL object. This is the state of the url in the process of resolving or reversing an url. It's a two-way street: when resolving, it starts out as a full path, and the Constraints chip away at the path, while the set of constraints and extracted argument grows. When reversing, it starts out as a set of constraints and arguments, and reconstructs the partial urls from those constraints and arguments until a full url path is reconstructed. It shifts some of the logic from the Resolver to the URL, so that it is easier to extend the Resolver. It is also a simple container that allows any Constraint access to the full request. Last but not least, it allows to dynamically build an url against the current request. This is useful if e.g. a constraint matches a different subdomain than the current request, so that a link automatically points to the right domain. I'm looking forwards to your feedback. Thanks, Marten -- You received this message because you are subscribed to the Google Groups "Django developers (Contributions to Django itself)" group. To unsubscribe from this group and stop receiving emails from it, send an email to django-developers+unsubscr...@googlegroups.com. To post to this group, send email to django-developers@googlegroups.com. Visit this group at http://groups.google.com/group/django-developers. To view this discussion on the web visit https://groups.google.com/d/msgid/django-developers/3cb36c11-16ee-4702-92a3-f9afb177bbca%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
